Welcome to the Forum,
A 24V System can support an Inverter up to 4000W + Surge. At 4000W, that is 166A Amps being pulled from the Battery Pack.
I am also Offgrid in the North (not as far up as you) running a 24V/4000W system with 2Kw of panels. You can have a peek at the "About my system" link in my signature on more details about my setup. I do not run an AIO (All-In-One) system like MPP or Growatt.
I use a Generator in winter on those low sun days (hoping I can solve that this year) to charge my Battery Bank. My Bank was 910AH/23kWh which for me is 6 days runtime in "conserve" mode. I am reconfiguring my battery bank now, bringing it to 1190AH/30kWh for 7.5 days autonomy. My Samlex Inverter/Charger is capable of pushing 100A Charge rate but I've set this to 80A to keep things nice & reasonable. When using my Genset, it is pulling 120V/22A to 25A (it floats due to Pass-Through power being provided to Cabin) from the L5:30 (120V/30A) plug. NB My AC system is 120VAC only as I have no need for 240VAC. The Samlex Inverter is 120V only as is its charging input.
A Generator needs to be sized so that it can deliver as much Volts/Amps as required by the Charging System. All-In-Ones can be either 120V or 240V, they can take either 120V/240V for charging depending on model. There should also be an Overhead Margin so you do not run the generator at its maximum generating capacity (that will only hasten its demise) Therefore I suggest a model that has a minimum of 1000W more Running Watts that is required to fully support your charging system. So if the Charger requires 120V/2500W/21A the Genset should be at least a 3500W "Running Watts" unit. Also if your system has Pass-Through power, meaning it can charge batteries AND provide power to the AC Circuits as well, that amp demand will go up and fluctuate during use.
NOTE: Not all Generators can be used with an Auto-Start system !
Most systems have AGS (Auto-Generator-Start) capabilities which signals a GSCM (Generator Start Control Module) to start, stop a generator.
Here is a Link to one of the best GSCM's for our usage:
http://atkinsonelectronics.com/gscm-mini-60hz-usa-canada/
Link to the PDF DOC which you can search through to see if you have a Compatible Genset. IF the Generator is not listed in there, then it is unlikely that ANY GSCM will work with it...
http://atkinsonelectronics.com/content/product_pdfs/All Hookup Diagrams Merged.pdf
Your 1st order of business is to determine how many Amp Hours you use per day. Power Usage Assement.
- This will help determine the sizing of your "basic" battery system
Next, you will have to decide how many days autonomy you want without any charging (solar/genset or other). Most folks go with 3 days but some of us need more due to lack of sunshine in winter...
- This makes sure the battery system is big enough for your needs.
NEXT, once you know the battery size, then you have to figure out how much solar panel it will take to charge that battery bank. This is where it gets trickier because it's hard to replace 5 days of battery use in just "5 hours". This is where you think about 1/3rd charge (for full bank) per full sun day and you have to hedge it a bit. Much depends on your Lowest Sun Hour days and Highest Sun hour days. and how you want to manage that.
Solar System - All in One Systems:
Victron is obviously a Top Brand Tier-1 product. These cost more but the adage of "you get what you pay for" is very true in this instance.
Growatt is both Tier-1 & Tier-2 product levels. These are very good units which are feature rich as well and a Good Dollar Value for the quality.
MPP-Solar is Tier-2 & Tier-3 product. These are also quite good but have a few less features & functions included (a few can be added on at extra $).
Most of these can be "stacked" to increase capacity for both the solar & inversion side.
Given you are Rural & Remote and will not have time to furtle with problems should something go awry, you need / want dependability & reliability. To that end, I will "tell you" to avoid High Frequency (HF) Inverters and stick ONLY to Low Frequency (LF) Inverters. They are more costly (not terribly) and they are far more reliable and can handle 3X Surge rates whereas HF units can only do 2X Surge.
REF:
Understand the difference between high frequency and low frequency inverters with this quick article.
www.magnum-dimensions.com
LESSONS LEARNED:
It is not unusual for people to come up with a guesstimate and say they need 3000W Inverter, assuming that at most the system will only pull that much with your usage. Within a year, about 75% of folks realize they undershot and then upgrade to the next model or two up. That get's expensive really fast PLUS you end up charging battery cables etc and your head will be spinning and Blue Air will be emanating from your mouth ! MRS TOO 99.9% of the Time as well ! (something to always avoid when possible).
Battery to Inverter Cable. I always suggest to folks to go One Size above what is required (no penalty for bigger) so they only have to buy it once, the stuff is crazy pricey. So if you work out the specs and it requires 3/0 Wire to meet the "need" I suggest going with 4/0 which provides more throughput potential and reduced resistance and is also a bit of future proofing. BTDT.
By using a 4000W instead of a 3000W Inverter there is no extra "penalty" to pay for having the "delivering capacity" but can save you much grief. So PLEASE Consider, that a bit bigger then you imagine is not a bad thing, especially if it does not cost you a heap extra.
Examples:
I run my Coffee Maker it pulls 50A from the battery for 6 minutes while brewing (no warmer, it has a thermal insulated carafe).
I run my Microwave (Panasonic 1200W Inverter type) and it pulls 60-70A from teh battery while running.
My GrundFos SQ-5 Deep Well Pump is a 120VAC Soft Start unit, which is 260' deep, pushes to a 50 Gal. Pressure tank then 75' to Cabin. It starts at 550W and stages up to 1100W by the time it reaches the 50-PSI cutoff point. At 1100W it is pulling roughly 45A from the battery bank.
Let me put this another way, 120V/1000W = 8.3A uncorrected. 120V/4000W = 33.3A uncorrected. Deliverable to AC Side.
With a 120V/4000W Inverter, it can only deliver 120 Volts @ 33A at any given time + Surge Handling for motor starts (fridge, AC unit, Pump etc)
To give you an example... As I sit here writing this, my HP EliteDesk i7 PC is running with an LG 47" TV as a screen, a Router, Satelite modem, 2 LED lights, fridge is NOT going and I am using 7.2A off my battery bank, with Fridge running it would be 10.1A. I also have a few wall warts plugged in as well as the idle power on both my On-Demand water heaters.
A GOTCHA that get's New People.
Inverter Efficiency ! That blighter lurks in the wide open. Many of the lower cost "Value" Tier3 & even Tier-2 Inverters are between 84-88 % efficient. Some Tier-2 do better than that, Tier-1 products tend to be more efficient like Victron at 94% or my Samlex at 94%. Believe it or not, that does make a
significant difference over a 24 hour period. It is worth getting a higher efficiency unit as that will return that investment with longer battery life (more juice).
Lots to chomp on, Hope it helps, Good Luck
Steve
PS, look at the links in my Signature, a few will likely help you along your path.
